1. Field of the Invention
The present invention is directed to a compression pressure reduction apparatus for an internal combustion engine and to an engine having a pressure relief apparatus to reduce compression pressure during start up and minimize the power needed by the starter motor to crank the engine.
2. Description of the Prior Art
Internal combustion engines must be turned over using battery power to start the engine and have ignition occur. During the start up phase, the pistons moving up in the cylinders create a compression pressure that must be overcome in order to crank the engine. This compression pressure creates additional forces during start up and a greater drain on the battery and stress to the starter motor and other components.
Devices are known that reduce the compression pressure in internal combustion engines during start up. However, these devices suffer from several undesirable attributes that make them less efficient and impractical. Some devices vent gases to the atmosphere during startup to relieve compression pressure. However, such devices do not provide proper filtering or muffling of these gases. Such gases typically contain unburned fuel, oil and other airborne contaminants and the engine surfaces may acquire a residue from the venting of these gases during start up. Such a condition is messy and makes the engines less attractive. Some devices do not provide remote actuation, making access to these devices difficult for the operator.
U.S. Pat. No. 5,957,097 discloses an internal combustion engine with automatic compression relief. The compression relief system uses the existing valves of each cylinder and a special camshaft. The camshaft has cams that engage the valves and keep them in a partially open position. At higher pressures, biasing forces from springs are overcome to disengage the cams, so the valves return to their normal operating position. Such a device requires an expensive modified camshaft and is quite complicated. The camshaft cannot be manually selectively activated.
It can be seen then that a new and improved compression pressure reduction system is needed that overcomes the problems associated with the prior art. Such a compression pressure reduction system should be easily actuated and should vent gases to the exhaust system. Moreover, such a device should provide valving to a plurality of cylinders with actuation from a single source. Such a device should use existing cams and cylinder valves and be easily mounted to the engine. The present invention addresses these as well as other problems associated with the prior art.
The present invention relates to a compression pressure reduction device for an internal combustion engine, and more particularly, to a pressure relief device to reduce pressure from compression during startup.
An internal combustion engine of the present invention includes a cylinder head with a compression relief valve connected by a duct to the combustion chamber. The pressure relief valve associated with each cylinder threadably mounts in a bore on the top of the cylinder head. A duct leads from the combustion chamber at the top of the cylinder to the pressure relief valve. A second duct leads from the bore to the exhaust port of the cylinder head. In this manner, gases that may include unburned fuel and oil are directed through the exhaust system, rather than being vented to the atmosphere. Each cylinder has an associated pressure relief valve and all the relief valves are actuated from a single actuator in preferred embodiments.
In a first embodiment of the present invention, the pressure relief valve is mechanically actuated and includes a valve body with a plunger in an axial bore formed in the valve body. The valve body includes exit holes aligned with the duct to the exhaust port so that when the plunger is open, gases may vent through the valve body to the exhaust port. The plunger includes a widened end portion with a seating surface that seats against the end of the valve body in a closed position and spaced apart from the valve body in the open position. The valve body mounts to a connector member mounting to a cam housing. The cam housing includes a cam engaging the top of the plunger and pivotally mounting to the cam housing. A cable connects to the cam to pivot the cam to a closed position and push the plunger to an open position. The cable connects with cables from other cylinders to a manually operated remote actuator that has a knob that is pulled to retract the cable and pivot the cam, thereby opening the valve. A spring in the valve biases the plunger toward the closed position. Spring loaded detent bearings engage a recess in the plunger body and hold the plunger in the open position, with the plunger head extended from the valve body.
According to a second embodiment of the present invention, an electrically actuated pressure relief valve mounts in the cylinder head associated with each cylinder. A plunger and body are similar to the mechanically actuated first embodiment and mount in the same manner. In the second embodiment, a solenoid is utilized to actuate the plunger. A solenoid body includes internal integral coils. An iron core extends into the solenoid body within the coil and pushes the plunger to the open position when it is energized. A spring biases the sliding solenoid core toward the closed position. A single actuator may energize wiring leads to the starter or another circuit so that the pressure relief valves associated with the cylinders are actuated together. In addition, if the circuit is tied in with the starter, the solenoid is de-energized and the valve closes when the button is released, so that the valve is only open for the required time.
These features of novelty and various other advantages, which characterize the invention, are pointed out with particularity in the claims annexed hereto and forming a part hereof However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.